Clutch



l9, 19.46.- D. FIRTH EI'AL 2,396,647

I cnuwcu Filed. April 22, 1942' '4 sheets-sheet 1 INVENTCRS.

7 CZZemnderZTBoaZey March 9; 1946.

- cwmca Filed April 22, 1942 4 Sheets-Sheet 2' I INKENTORS. 2

D. FIRTH ETAL 2,396,647

I CLUTCH I Filed April 22, 1942 4 Sheets-Sheet 3 19, 1946. FIRTH AL I CLUTCH Filed April 22, 1942 4 Sheets-Sheet 4 Patented Mar. 19, 1946 CLUTCH David Firth, South Bend, and'Alexander TsBodlc,

Mishawaka, Ind., assignorsto Dodge Manufacturing Corporation, Mishawaka, Ind., a corporation of Indiana Application April 22, 1942. Serial No. 439,980

10 Claims This invention relates to friction clutches for use in machinery drives and power transmissions. The general object of'the invention is to provide animprovedfriction clutch of the type comprising confronting members carried by and in driving connection-with a shaft and cooperable to grip an interposed friction disc carried by the rotatable machine element which is to be clutched to the shaft. .More particularly, the invention aims to improve clutches of said type with respect to thegeneral construction and organization thereof and with respect to the mechanism by which the clutch members are forced into coaction. Further objects ancillary or subsidiary to those stated will be apparent from the following description with reference to the accompanying drawings, in which:

Fig. 1 is a section taken longitudinally of and through the axis of a clutch of one practicable construction embodying the invention, showing the clutch in-applied or closed condition.

Fig.2 is a detail plan view of one of the clutch toggles and the parts between whichit acts.

Fig. 3 is a rear elevation of such toggle.

Fig. iis an enlarged view of a portion of Fig.1,

showing the clutch inreleased and open condi-' tion.

,Fig. 5 isa detail view showing in front elevation a fragment of the adjustingnut Which sustains backward thrust of the clutch goggles, and showing in section an element of one of said toggles.

Fig. 6 is a horizontal section taken on the line 6--6 of Fig. 5.

Fig. '7 is a section'taken on the line .'l--:'i of Fig. 1, looking in the direction of thearrows and showing in rear elevation parts beyond the plane on which the section is taken.

Fig.8 is a partial sectional view of a modified clutch embodying the generic invention butnot all specific features thereof.

iFig. 9jis a cross sectional view-taken on the line 9-9 of Fig. 8, looking in the direction of the arrows.

Fig. 10 is a sectional view of another modified clutch embodying the generic invention but not all specific features thereof.

Fig.11 is a cross sectional View taken on the line 1 l'|l of Fig. 10,1ooking inthe direction of the arrows.

Each of the several clutches shown in the drawings is represented as installed on a shaft 1 for use in clutching thereto an independently rotatable machine element. The shaft I may be considered to represent either ,a driving or a driven shaft. A-rotatable element to be clutched thereto is represented injFig. "1 by a disc-carrying ring 2 which may be either a part of or attached to a pulley, flywheel or other member rotatable independently of and coaxially with the shaft. In Fig.1, said ring Zis shown'bolted to a bell-shaped extension 3 from a sleeved loose on the shaft, on which sleeve may be fixed the hub of a pulley or other member.

Referring first toFigs. 1 to! inclusive, the illus-' trative clutch therein shown comprises a pair of confrontingmembers 5 and Scooperable to clamp or squeeze an interposed friction disc I. Said discmay .be of fibrous or other suitable material having a high coefficient of friction. It is shown as an-annular steelplate faced on opposite sides with attached liners 8 of such material.

The clutch member 5, fixed to or mounted on the shaft in driving connection therewith, carries on-its hub the-member 6, the latter being in driving connection with but movable axially relative to said carrying member '5. As shown, the hub 9 of said member 5-is keyed to the shaft by a'driving key-l0, and said member 6 is mounted directly on a portion -of-said hub extending beyond the clutch face of said member-5. Said extended portion ofsaid hubis shown formed with peripheral gear-like teeth I I, interfitted with and slidably engaged by'correspondingly formed internal teeth of the-clutch member 6, whereby said member 6 is held firmly on said hub with a strong and efficient driving connection but with freedom to move axially toward and away from its clutch member .5. Assembly of the two clutch members 5 and-6 is easily accomplished by simply slipping thermember 6 onthe projecting hub of the member-5.

Thefriction disc I is held by and in driving connection with the rotatable'member or element With carri'es it. .It is shown formed with peripheral teeth I-2 interfitted with correspondingly formed internal-teeth of the ring .2, wherebysaid disc is properly held with capability of axial movement as is desirable in the operations of applying and releasing the clutch.

Springs l3 arrangedand reacting between the clutch members 5 and 6 exert pressure against the axially movable member 6 ma direction to force it away from themember 5, whereby to promote or assure separation of the coactive friction faces of the clutch whenreleased. These springs are arranged about the clutch shaft in alternation with the toggles presently to be described.

Coaction of the clutch members 5 and 6 to clamp or squeeze the interposed friction disc is effected by actuation of toggles arranged between and so as to exert opposing thrusts on the movable. clutch member 6 and a thrust collar l4 behind it, which thrust collar is carried by the hub 9 and held from displacement rearwardly by connection with said hub; said collar thus functioning to sustain the back thrust of the toggles and to transfer such thrust to said hub of the clutch member I. As shown, said thrust collar i4 is supported on a tubular support or projec.

tion I 5 extending from said hub rearwardly of or beyond the back of the movable clutch member and enclosing the shaft; the collar I4 being mounted on said projection'or support and held thereto by screw threaded engagement therewith. Thus this thrust collar l4 functions also as an adjusting nut. By rotating-or turning said sides of the shaft could be employed, but three arranged as shown are preferred for more equal distribution of the pressure applied by the several toggles. 'The toggles are actuated by means carried byan axially movable clutch shifter 16 slidable on the shaft and operable by anyappropriate means as',for example, a clutch throw leverinot shown) having a yoked arm engaging pintles ll'on a collar l8 swiveled to said clutch shifter. a 1

Q'A's'shown, the clutch shifter [6 comprises a sleeve slidable on the shaft and within the tubular support or-nut holder I?) which provides a guide therefor independently of or in addition to that provided by the shaft. Said sleeve is formed or 4 provided with -toggle-actuating means represented by the shouldered fore end, portion i9 of said s'leev'athe annular shoulder of which is provided by forrning an annular groove 28 in said sleeve near its fore end. It will be apparent that'the annular means I9 is the functional equivalent of a plurality of angularly spaced devices corresponding in form and position'to the respective parts of said means H3 which are in operative association with the respective toggles. In othcrwords, the means l9 combines a plurality of toggle-actuating parts or devices in a simple annularform. The tubular support l 5 is formed with longitudinal slots 2| through which elements of the toggles extend for operative engagement with said toggle-actuating means I9. The saidmeans l9 may be considered as a camming means coactive with said toggle elements for actuating the toggles to apply the clutch and forreversely operating them to release the clutch. I v 1 Each togglecomprises a lever 22 having a fulcrum bearing against the thrust collar or nut i4, and an element 23 pivoted by the fulcrum pin 24 to the movable clutch member 6 and by the knuckle pin 25 to said lever 22. In the sp cific construction shown, the element 23 is pivoted by the pin 24 to and between 'apair of supporting lugs 26 on the back of the clutch memher a and the lever 22,enteringa slot'2l said element 23, is pivoted to and between the cars 28 thereof by the pin 25. Said element 23, shown as an irregularly shaped block-like piece, provides a short toggle arm combined with and at the outer end of a relatively long operating arm or lever for engagement by the actuating means i9. 7 The short toggle arm referredto is represented by the line connecting the centers of the pivotpins' 24 and 25. In mechanical effect, said element 23 is a kind of angle lever fulcrummed on .'the pin 25 and having the respective arms referred to, i. e. a short toggle arm connected by the knuckle pin 25 to the other toggle arm or lever 22, and a relatively long inwardly extendingoperating arm. By forming said element as shown, instead of in ordinary angle lever form, there are gained not only increased strength of the levering element but also mechanical advantage in power application, inasmuch as force applied by the actuating means [9 to the operating endof said element or lever is transferred through its body directly to the knuckle pin 25, with the effect of giving greater leverage for power application than that represented by the distance from the center of the fulcrum pin 24 to the actuating means l9. At its inner or operating end, said eleme'nt'or lever 23 is shown formed with a cut out portion providing a recess 29 and arm projections 3! and 30 for engagement by the actuating means I9 on forward and backward movements thereof.

It will be understood that the foregoing description of an individual toggle is applicable to the several toggles which are similarly constructed and arranged for simultaneous actuation'by the clutch shifter by coaction of the actuating means i 9 there'on'with the lever arm projections 30 and 3! of the elements or levers 23 of the respective toggles.

The operation is as follows: In the released condition of the clutch, the toggles being relaxed as shown in Fig. 4, the toggle elements or levers 23 are in position for engagement of their fore arm projections 30. by theshouldered fore end IQ of the shifter sleeve E6 on forward movement thereof, while the rear arm projections 3| are retracted or positioned outwardly away from said sleeve. To apply the clutch, the shifter sleeve l6 isforced forward or to the left from the position shown in Fig. 4. In this movement, the fore end of said sleeve or actuating means I9 thereof, pushing against the rounded tips of the arm projections 30, forcibly swings said elements or levers 23 in a clockwise direction or forwardly and inwardly from the position shown in Fig. 4 to the position shown in Fig. 1, thereby forcibly actuating or stressingthe toggles to force the clutch member 6 into disc-clamping c'oaction with the clutch member I The arrangement and adjustment of the clutch mechanism is preferably such as to allow complete straightening of the toggles in the clutch-applying operation, and the locking of the clutch in'applied or closed condition by forcing the toggle knuckles'25'slightly inwardly past dead center positions, i. c. with the centers of the knuckle pins 25 slightly inwardly past the lines of centers of the fulcrum pins 24 and fulcrums of the levers 22. When the clutch is applied, the shaft 1, clutch members Sand 6, interposed'friction disc I and its carrier ring 2, rotate as a rigid unit, as is apparent. In the clutch applying operation, as the shifter sleeve l6 moves forward and the toggle elements orlevers 23 swing to the position shown in Fig. 1, the shoulder at 19 enters the recesses 29 while the shoulder or into the groove 20 in the specific const uction llu trate To re e se the clutch. the hifter sl eve l is f ce ba w d o tothe right from the position shownin Fig. 1. In this movement-the shoulder at l9 pushing and cam.-

ming against the rounded arm projections -3l forcibly swing the toggle elements or levers 23 in a counter clockwise direction or rearwardly and outwarly from the position shown in Fig. 1 towardthat shown in Fig. 4. It will beobserved that t eleas pe ati s o it ve, bein only assisted but not depending upon the springs l 3. Nor could the springs initiate release while the toggles are either straight or looked as aforesaid by having the centers of the toggle knuckles li htl in a d y past de d enter po itio s- On th he h nd th s in s l3 pr mo e Orassl prompt backward movement of the clutch member 6 torelease the clutch disc I as soon as the toggles are flexed outwardly to relax them. In the releasing operation, the shoulder at I!) pushes outwardly and under thearm projections3 I, after wh ch ther m be co nu d backward mo ement of the sleeve l6 while the to gle elements or levers 23 may swing to th positions shown in Fig. 4by the momentum given them'in the releasing operation and by the force of the sp i B- To permit adjustment for wear compensation byrotation of the nut M, the toggle levers 22 of the several toggles have their rear ends bearing pivotly against but in sliding engagement with an annular seat therefor on said nut. In the illustrative construction, such seat is provided by an annular groove 32 of semi-circular or particircular cross section, and the toggle levers 22 have rear rounded fulcrum portions bearing against said nut in said groove and slidably fitted thereinto permit rotation of the nut.

As a specific feature of the invention, the construction shown in Figs. 4 to 6 is provided. According to this construction, the toggle lever 22 of each toggle has a rear fulcrum portion in the form of a pintle 33 with a straight cylindrical bearing surface perpendicular to the plane of operation of the toggle but of sufficiently less radius than the radius of the cross sectionof the groove 32 .to fit slidably therein. At the middle or center of the groove 32 is a narrow flat surface 34 against which such pintle bears, the cross section of said flat surface being a short chord of a circle coincident with the cross section of the wall of the groove. By virtue of this construction the pintle bears for its full length against said flat surface 34, as shown in Fig. 6, and wear between the contacting bearing surfaces of the pintle and nut isnot of serious moment. There may be sliding contact or near contact between the pintle and wall of the groove at or near the points indicated at 35, 36 and 31 in Fig. 5.

The fulcrum end portions of the toggle levers 22 could be spherical and fit in a semicircular groove in the thrustnut, but in that case there would be only line contact between the lever fulcrums and the nut and under excessive pressure there might be objectionable wear of the contacting bearing surfaces. The fulcrum portions of said toggle levers 22 could also be pintles of arcuate form to fit a semicircular groove, but such a construction would be more expensive and involve diificult machining. The construction described with reference to Figs. to 7 is considered more practicable than and preferable to the o ersm t o ed I The :nut [.4 .may be held in its :adjustedposbtion .or' against accidental zturning by a springactuated detent.pin;38 engagingoneof'a circular series of holes 39 .insaid nut, said pin being slidablymounted inaholderidfl thereforatz- .tached tothe hub .projection l5 and being provided with a head or knob Al by which the pin can .be retractedfrom .theuhole 39 in which it engages. As the thrust collar or nut is :turned the angular distances from one .pin hole 3.9 :to the next, .the pin :38 unless held retracted will snap into such next hole.

It Will be apparent that the illustrative con.- struction above described provides a clutchof .a highly practicable and efficient character, and one which is well adapted for use in'high speed machinery and power transmissions. Theconstruction is sturdy and compact, comparatively simple,.composed of a relativelyfew parts, easily assembled, and susceptible of manufacture less expensively than certain prior clutches of .simi-' lar type. In operation, the clutch members are forced into .coaction by actuation of toggle mechanism of advantageous character, and the release operation is positive, .permittingthe em.-

ployment of toggles which are forced to and preferablyslightly past dead center positions for locking the clutch in the applied or closed condition and relieving the springs l3 of :the duty of flexing the toggles outwardly for the releasing operation. With other advantageous features and characteristics, the clutch is conveniently adjustable for taking up wear of the coacting friction surfaces. Thecharacter of the clutch is such that it maybe used for a long period of service without the necessity of such adjustment. When adjustment becomes necessary, it can be easily accomplished by simply turning the adjusting nut M the distance from one hole 39 to the next. The adjustment affects the axial relation of the nut to the clutch memher 1, thereby affecting the actual relation of the clutch members 5 and 6 in the closed con- ,dition of the clutch, but without affecting the relative shift of the operating elements. There being no effect upon the throw, the clutch is welladapted for "installations embodying a me chanical operator for throwing in and out the clutch. In short, the operating characteristics and capabilities desirable for a highly "practicable and efficient clutch of the type referred to are obtained in a construction of generally improved character.

The several capabilities and advantages above referred to, except adjustment merely by turning of an adjusting nut, are also had or obtained in the clutches of modified construction shown in Figs. 8 to 11 which,as'hereinbefore indicated, embody the generic invention herein set forth but not all of the specifically novel and inventive features of the construction shown in Figs. 1 to 7.

In Figs. 8 and 9, the principal elements corresponding to those of the clutch first described are the members 5* and 6 interposed friction disc l clutch hub 9 tubular hub projection I li thrust collar I4 toggles comprising elements 22= and 23 and the clutch shifter i having the toggle-actuating means [99 The construction shown in Figs. 8 and 9 is substantially identical to that of the first described clutch except that i in Figs. 8 and 9 the thrust collar I i instead from displacement rearwardly by connection to the hub by means. of bolts 43, by adJ'ustrnent of theheads 44 of which the axial relationship of the thrust collar to the clutch member can be adjusted. Said thrust collar 14* is shown as an annular member of undulating form having alternating forwardly and rearwardly offset portions 45 and 46 joined by thecdnnectingportions 41. The bolts 43 are connected with the forwardly offset portions of .said thrust collar, and the rear toggle elementsor levers 22 bear against the rearwardly offset portions 48, As shown, the toggle levers '22 have their pintles 33 bearing in seats 32 ofthe said rear portions 46 of said thrust collar. Said pintles 33 may be ball-shapedor have hemispherical portions fitted in hemispherical sockets in the thrust collar, or the pintles 33 may be. formed like the pintles -33 in Figs. 5 and 6 and. said seats 32 may be provided as straight grooves of semi-circular crosss section. In Fig. 8 a set screw is shown at '48 engaging a hole in the shaft key Ill for securing the clutch hub. in fixed relation to the shaft key.

. Substantially similar in construction and mode of operation to the clutch first described is that shown in Figs. 10 and 11 except that its toggle actuating means 19 instead of being formed on the fore end of a clutch shifter sleeve slidable within a hub projection, are formed as a plurality of such means on the fore ends of rods 49 extending longitudinally from and rigidly affixed to a clutch shifter l6 slidable on the shaft, and the back thrust of the. toggles is taken by a thrust collar l4 fitted slidably on a hub extension IS and held in'place or from displacement rearwardly by bolts'crews 50 manipulatable for adjusting the axial relation of said thrust collar to the clutch hub 9 said rods 49' being slidably fitted in holes therefor in said thrust collar. In Figs. 10 and 11, the disc-clamping clutch members and interposed disc are designated-by the reference characters 5 6 1, and the toggle elements by the reference characters 22 and 23 In Fig. 8, the set screw 5! engages a hole in the shaft key lfl to-secure the clutch hub in fixed relation thereto. I

We claim as our invention: 7 A

l. A clutch comprising disc-clamping members, one carrying and in driving connection with the other which is movable axially relative to said one, a thrust collar carried by said carrying memher behind said movable member and held from displacement rearwardly by connection with said carrying member, toggles comprising knucklejointed elements arranged between and for thrust of said elements oppositely against said thrust collar and movable member, the toggle elements being pivotally jointed at opposite sides of the toggle knuckles to said movable member and thrust collar, said toggles being operable inwardly to stress them, the elements of said toggles fulcrummecl on said movable member consisting of levers providing short toggle arms and relatively long inwardly extending operating arms, and axially movable toggle actuating means having shoulder means on the fore end thereof, said long arms having projections engageable by said fore end on forward movement of said means and projections which swing behind said shoulder means during such movement, said toggles'bein'g operable to release theclutch by coaction of said shoulder means with said last mentioned projecvented from; turning relative thereto byra spline .tions on backward movement of said actuatin -42,'rand held thrust-sustaining position or means 2;;A clutch one carried on the hub ofthe other in driving comprising disc-clamping members,

connection therewith and movable axially toward and from said other member, said hub having a tubular "projection extending rearwardly of said movable member, a thrust collar-supported on 'saidprojection and held from displacement rearwardly by connection with said hub, toggles comprising knuckle-jointed elements arranged betweenand for thrust of said elements oppositely againstsaid collar and movable member, corresponding elements of said toggles providing-short toggle arms and relatively long inwardly extendingoperating arms, said tubular projection having longitudinal slots into which said operating arms extend, and an axially movable clutch shifter having a sleeve portion engageable with said operating arms for actuating said toggles.

3. A clutch comprising disc-clamping members, one carried on the hub of the other in driving (connection therewith and movable axially relative thereto, a thrust collar behind said movable membcr carried by said hub and held from displacement rearwardly by connection with said hub, toggles comprising knuckle-jointed elements arranged between and for thrust of said elements oppositely against said collar and movable memher, the toggle elements being pivotally jointed at opposite sides of the toggle knuckles to said movable member and thrust collar, corresponding elements of said toggles being levers fulcrumed on said movable member providing short toggle arms and relatively long inwardly extending operating arms, theother elements'of said toggles being levers pivotall connected to said short arms and fulcrummed on said thrust collar, an axially movable clutch shifter, and rods rigidly afiixed to and extending forwardly therefrom having means engageable with said long arms for actuating said toggles.

4. A clutch comprising disc-clamping members, one carried by the hub of the other in driving connection therewith and movable axially relative'thereto, said hub having a'tubular projection extending beyond said movable member, an

adjusting nut mounted behind said movable member on said projection in screw-threaded en-' gagement therewith, toggles comprising knucklejointed elements arranged between and for thrust of'said elements oppositely against said nut and movable member, the toggle elements bearing against said nut being in'slidable engagement therewith to permit rotation of the nut for ad'- justment, andaxially movable means for actuating said toggles, said nut having an annular groove with a narrow fiat bottom or central surface which in cross section is a short cord of a circle coincident with the cross section of said groove, and the toggle elements engaging said nut having fulcrum portions comprising pintles with straight cylindrical surfaces perpendicular to the planes of operation'of the toggles and of less radius than the radius of the cross section of said groove, said pintles bearing against said ring "behind saidplate, toggles comprising slidably fitted in knuckle-jointed members arranged between and for thrust of said members oppositely against said ring and plate for forcing the latter into coaction with said opposing member, the toggle members being pivotally jointed at opposite sides of the toggle knuckles to said ring and plate, corresponding members of said toggles having inwardly extending arms, a hub carrying said plate and opposing member in driving connection therewith and having an extension carrying said ring, and axially shiftable means extending through said ring and operatively engageable with said arms both on protractive and retractive movement of said means for forcing the toggles by positive action to and from self-locked clutchapplying position.

6. In a friction disc clutch having an axially shiftable clutch plate and an opposing member with which it coacts to clamp or squeeze interposed friction disc means, the combination comprising an axially adjustable thrust-sustaining ring behind said plate, toggles comprising knuckle-jointed members arranged between and for thrust of said members oppositely against said ring and plate for forcing the latter into coaction with said opposing member, the toggle members being pivotally jointed at opposite sides of the toggle knuckles to said ring and plate, and corresponding members of said toggles having inwardly extending arms, a hub carrying said plate and opposing member in driving connection therewith and having an extension carrying said ring, and axially shiftable means extending through said ring and operatively engageable with said arms both on 'protractive and retractive movement of said means for forcing the toggles by positive action to and from selflocked clutch-applying position, there being operative connection between said arms andshiftable means permitting withdrawal of the latter from engagement with said arms by continued retractive movement of said shiftable means after forcing the toggles to position for clutch-release.

7. In a friction disc clutch having an axially shiftable clutch plate and an opposing member with which it coacts to clamp or squeeze interposed friction disc means, the combination .comprising an axially adjustable thrust-sustaining ring behind said plate, toggles comprising knuckle-jointed members arranged between and for thrust of said members oppositely against said ring and plate for forcing the latter into coaction with said opposing member, the toggle members being pivotally jointed at opposite sides of the toggle knuckles to said ring and plate, corresponding members of said toggles having inwardly extending arms, and axially shiftable means extending through said ring and engageable with said arms for forcing the toggles by positive action to and from self-locked clutch-applying position, said arms having recesses and said shiftable means having shoulder portions which enter said recesses and behind which portions of said arms swing as said means is forced to position to apply the clutch, whereby reverse operation of said shiftable means forces the toggles to clutch-releasing position by coaction of said shoulder portions with said arm portions and said arms are swung to position to free said means from engagement therewith.

8. In a friction disc clutch having an axially shiftable clutch plate and an opposing member with which it coacts to clamp or squeeze interposed friction disc means, the combination comprising an axially adjustable thrust-sustaining ring behind said plate, toggles comprising knuckle-jointed members arranged between and for thrust of said members oppositely against said ring and plate for forcing the latter into coaction with said opposing member, the toggle members being pivotally jointed at opposite sides of the toggle knuckles to said ring and plate, said toggles being operable inwardly for stressinig them, the members of said toggles which are fulcrummed on said plate having inwardly extending arms, and axially shiftable means cooperable with said arms for operating said toggles.

9. In a friction disc clutch having an axially shiftable clutch plate and an opposing member with which it coacts to clamp or squeeze interposed friction disc means, the combination comprising an axially adjustable thrust-sustaining ring behind said plate, toggles comprising knuckle-jointed members arranged between and for thrust of said members oppositely against said ring and plate for forcing the latter into coaction with said opposing member, the toggle members being pivotally jointed at opposite sides of the toggle knuckles to said ring and plate, said toggles being operable inwardly for stressing.

them, the members of said toggles which are fulcrummed on said plate having inwardly extending arms, and axially shiftable means cooperable with said arms for operating said toggles, said shiftable means having shoulder portions on the fore end thereof and said arms having projections pushed by said means on forward movement thereof and other projections which swing behind said shoulder portions during such movement, substantially as and for the purpose described.

10. In a friction clisc clutch having an axially shiftable clutch plate and an opposing member with which it coacts to clamp or squeeze interposed friction disc means, the combination comprising an axially adjustable thrust-sustaining ring behind said plate, toggles comprising knuckler jointed members arranged between and so for thrust of said members oppositely against said ring and plate for forcing the latter into coaction with said opposing member, the toggle members being pivotally jointed at opposite sides of the toggle knuckles to said ring and plate, a hub carrying said plate and member in driving connection therewith and having an extension carrying said ring, said extension having longitudinal slots, corresponding members of said toggles having inwardly extending arms entering said slots, and axially shiftable means slidable in said extension and cooperable with said arms for operating said toggles.

DAVID FIRTH. ALEXANDER T. BODLE. 

